linux-kernel - [PATCH 5.17 006/772] riscv: Initialize thread pointer before calling C functions

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Date:   Tue,  7 Jun 2022 18:53:18 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Alexandre Ghiti <alexandre.ghiti@...onical.com>,
        Palmer Dabbelt <palmer@...osinc.com>
Subject: [PATCH 5.17 006/772] riscv: Initialize thread pointer before calling C functions

From: Alexandre Ghiti <alexandre.ghiti@...onical.com>

commit 35d33c76d68dfacc330a8eb477b51cc647c5a847 upstream.

Because of the stack canary feature that reads from the current task
structure the stack canary value, the thread pointer register "tp" must
be set before calling any C function from head.S: by chance, setup_vm
and all the functions that it calls does not seem to be part of the
functions where the canary check is done, but in the following commits,
some functions will.

Fixes: f2c9699f65557a31 ("riscv: Add STACKPROTECTOR supported")
Signed-off-by: Alexandre Ghiti <alexandre.ghiti@...onical.com>
Cc: stable@...r.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@...osinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/riscv/kernel/head.S |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -316,6 +316,7 @@ clear_bss_done:
 	REG_S a0, (a2)
 
 	/* Initialize page tables and relocate to virtual addresses */
+	la tp, init_task
 	la sp, init_thread_union + THREAD_SIZE
 	XIP_FIXUP_OFFSET sp
 #ifdef CONFIG_BUILTIN_DTB